JPH023366Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a chuck that prevents and tightens and grips a rotary cutting tool such as an end mill.

[Conventional technology] Conventionally, in machine tools such as machining centers, chucks (tool holders) have been used to attach tools such as end mills to the main spindle.
There was something shown in the publication.

FIG. 5 shows a chuck similar to that shown in Japanese Utility Model Publication No. 41-23987. In FIG. 5, reference numeral 1 denotes a holder main body having a tapered chuck tube 2 on the tip side, and a rotating tube 4 is fitted onto the outer peripheral surface of the chuck tube 2 via a number of needle rollers 3.
This chuck is made by fitting the shank portion 6a of the tool 6 into the inner surface of the chuck tube 2 via the collet 5, rotating the rotary tube 4, and compressing the chuck tube 2 by the needle roller 3. A shank portion 6a of a tool 6 is tightly gripped by the cylinder 2 via a collet 5. In addition, the rotating tube 4
By the reverse rotation of the chuck tube 2 and the collet 5, the compression is released and restored, thereby releasing the tightening of the shank portion 6a of the tool 6.

In the conventional chuck as described above, the chuck tube 2 is elastically deformed and contracted by the rotation of the rotary tube 4, which causes a large number of needle rollers 3 to rotate and revolve around the outer peripheral surface of the chuck tube 2 in a spiral manner. Since this contraction is performed in a wide pressing area by the needle roller 3, the shank portion 6a can be strongly tightened by the chuck tube 2, and the shank portion 6a can be held securely.

However, in recent years, tools have been improved and their cutting ability has improved, and as a result, the cutting resistance applied to the tool has increased. The lack of force causes relative slippage between the tool and the member that grips it, which adversely affects the cutting of the workpiece.

Therefore, as shown in FIG. 5, a lock bolt 7 that reaches inside the chuck tube 2 is threaded in the radial direction on the flange portion 1a of the holder body 1, and the tip of this bolt 7 is attached to the outer peripheral surface of the distal end of the shank portion 6a of the tool 6. By pressing against the notch 6b formed in the cutout 6b, the tool 6 is screwed and prevented from slipping in the rotational direction even if cutting resistance exceeding the gripping force of the chuck tube 2 through the collet 5 is applied to the tool 6. It has been proposed to do so.

[Problems to be solved by the invention] However, when attaching a tool to the conventional chuck configured as described above, a screw tightening operation is required when attaching the tool to the chuck body, and it is difficult to forget to tighten the lock bolt or during use. In addition, since the end of the shank of the tool is pressed against the lock bolt, the accuracy of gripping the tool by the holder body, that is, the concentricity of the chuck tube and the shank of the tool, may be poor, resulting in machining problems. There was a problem with the tools swinging around inside.

This idea was made to solve the above-mentioned problems. It eliminates the need for tool rotation locking operations, allows for reliable and stable tool rotation prevention, and also allows for secure and stable tool rotation prevention. The purpose is to provide a chuck that has good concentricity with the shank part and prevents the tool from swinging around during machining.

[Means for solving the problem] In this invention, the outer circumferential surface of a chuck tube provided at the tip side of the holder body is formed into a tapered shape, and a rotating tube is attached to the outer circumferential surface of the chuck tube via a large number of needle rollers. The shank portion of the tool is fitted onto the inner circumferential surface of the chuck tube through the collet, and the chuck tube is elastically deformed and compressed by the needle roller by rotation of the rotary tube. In the chuck for tightening and gripping the shank portion of the tool, a key is protruded from the outer circumferential surface of the collet, and a key groove is formed on the inner circumferential surface of the chuck cylinder over almost the entire length in the axial direction of the pressing area by the needle roller. , the key is slidably engaged with the keyway, the key is placed approximately in the center of the pressing area of the keyway in the axial direction, and the keyway is provided between the chuck tube and the collet. Space portions are formed on both sides of the key in the axial direction.

[Function] The chuck according to this invention has a key protruding from the outer circumferential surface of the collet into which the shank of the tool is inserted, and a key protruding from the inner circumferential surface of the chuck cylinder provided in the chuck body.
A key groove is formed over almost the entire axial length of the pressing area by the needle roller, the collet is inserted into the chuck cylinder, and the key is slidably engaged with the key groove, thereby ensuring that the tool does not rotate. In addition, since no screws such as lock bolts are used, there is no need to operate the tool to prevent rotation. Further, in the chuck according to this invention, the key provided on the collet is arranged approximately at the center in the axial direction of the pressing area of the key groove provided in the chuck tube, and a space is created between the chuck tube and the collet by the key groove. By forming the portions on both sides of the key in the axial direction, the collet and tool can be stably gripped with good concentricity on the holder body.

That is, the gap between the key groove provided on the inner circumferential surface of the chuck cylinder of the holder body and the key protruding from the outer circumferential surface of the collet into which the shank portion of the tool is inserted is small, and the key acts as a rigid body between the chuck cylinder and the key. When interposed between the chuck tube and the collector, when the chuck tube is pressed from the outer circumferential side by a needle roller provided on the outer circumferential surface of the chuck tube, first the key groove portion is elastically deformed in the circumferential direction, and the chuck in the cross section along the axial direction is The elastic deformation of the inner diameter of the cylinder does not begin uniformly in the entire pressing area in the direction of contraction of the inner diameter, but rather starts from approximately the center of the pressing area in the axial direction. As this deformation progresses, the deformation resistance at the axial center increases, and this deformation resistance and the deformation resistance at areas other than the center of the pressing area gradually approach each other, and accordingly, from the center to both axial ends. As the shrinkage deformation progresses, the inner circumferential surface of the chuck cylinder contracts. For this reason,
The contact between each surface of the keyway provided on the inner circumferential surface of the chuck cylinder and the key creates a resistance to the contraction and deformation of the chuck cylinder, and the axial center of the chuck cylinder cannot freely contract and deform, and temporarily The deformation stops, and during this time the shrinkage deformation of both ends progresses first. In other words,
The inner circumferential surface of the chuck cylinder is deformed such that the central portion in the axial direction is deformed into a chevron shape, and then the central portion and both end portions are deformed so as to be averaged. Therefore, if the inner peripheral surface of the chuck cylinder contracts evenly in the entire axial direction of the pressing area, the chuck cylinder will contract even if there is a gap between the inner peripheral surface of the chuck cylinder and the outer peripheral surface of the shank portion of the tool. As the gap disappears, the axial vibration between the chuck tube and the collet is successively corrected to be concentric, and when gripping is completed, the concentricity of the chuck tube, the collet, and the shank portion is high, that is, the gripping accuracy is improved.
(See Figures 4a and b) However, in the case of a tool like the one shown in Figure 5 in which the shank of a tool is fitted into a chuck cylinder without a keyway through a collet, it is difficult to insert the collet into the inner peripheral surface of the chuck cylinder. , there is a gap between this and the chuck tube, and as mentioned above, the axial center of the inner circumferential surface of the chuck tube deforms into a chevron shape, the chuck tube and the collet come into contact at the axial center, and then both ends When the collet is inserted into the chuck cylinder with its center misaligned by the gap and it first contacts the top of the chevron on the inner circumferential surface of the chuck, the entire pressing area in the axial direction is pressed in this state. As a result, when gripping is completed, the chuck cylinder and the collet are in a state of axial runout, resulting in low concentricity. (Figure 4a,
c) In addition, if the gap between the keyway provided on the inner peripheral surface of the chuck cylinder and the key provided on the outer peripheral surface of the collet into which the shank part of the tool is inserted is large and the key does not become a rigid body, the keyway The chuck tube is contracted due to the loose state between the key and the key. In this idea,
In the process of eliminating the gap between the chuck tube and the collector,
The part where the cross-sectional area is small in the keyway of the chuck tube first begins to contract and deform due to pressure from the outer periphery by the needle roller, and the chuck tube undergoes elastic deformation to bend at the keyway portion, and as this deformation progresses, the keyway portion Contraction resistance increases. Next, the shrinkage resistance of the portion of the chuck tube other than the keyway portion increases, and as it approaches the shrinkage resistance of the keyway portion, the portion other than the keyway portion shrinks and deforms behind the keyway portion. In addition, the chevron-shaped deformation at the center of the inner peripheral surface of the chuck cylinder in the axial cross section of the chuck cylinder occurs when the parts other than the key groove are contracted and deformed rather than the key groove. Compared to the one shown in FIG. 5, the amount of mountain-shaped deformation on the inner circumferential surface of the chuck cylinder is small, and therefore, the concentricity between the chuck cylinder, the collet, and the shank portion of the tool when gripping is completed is high.

[Example] An example of this invention will be described below with reference to Figures 1 to 4.
The diagram will be explained.

In FIGS. 1 and 2, 10 is a holder body, and the holder body 10 has a shank portion 10a formed at its base end, a flange portion 10b with a large outer diameter at its intermediate portion, and a chuck at its distal end. A cylinder 11 is formed. The chuck tube 11 has an outer circumferential surface that becomes smaller in diameter as it goes toward the distal end, that is, it is formed into a tapered surface. A large number of needle rollers 13 held by a cylindrical retainer 12 having the same taper as the tapered surface of the chuck cylinder 11 are supported over almost the entire length in the axial direction on the outer peripheral surface of the chuck cylinder 11. There is a rotating tube 14
are fitted. By spirally rotating the rotatable cylinder 14 with respect to the chuck cylinder 11, the chuck cylinder 11 is elastically deformed via the needle roller 13, so that the diameter thereof can be reduced.

A straight collet 15 for gripping a tool is fitted onto the inner peripheral surface of the chuck tube 11. As shown in FIG. 3, this collet 15 has slits formed at three equal intervals in the circumferential direction along the axial direction from the tip to near the end. Then, the shank portion 1 of the tool 16 inserted into the collet 15
The outer circumferential surface of the collet 6a is such that the entire surface of the fitted portion is in close contact with the inner circumferential surface of the collet 15.
Further, a straight cylindrical hole 11a corresponding to the outer diameter of the collet 15 is formed in the axis of the chuck tube 11. A key groove 17 parallel to the axis of the cylindrical hole 11a is formed in the peripheral wall surface of the cylindrical hole 11a over almost the entire length of the cylindrical hole 11a. The key groove 17 is formed on the outer peripheral surface of the collet 15 inserted into the cylindrical hole 11a.
A key 18 slidably engaged with the key 18 is fixed to the key 18,
The key 18 protrudes from the outer peripheral surface of the collet 15.

Further, in this embodiment, the shank portion 16a of the tool 16 is connected to the holder body 10 via the collet 15.
A key 18 that is fitted into a cylindrical hole 11a provided in the chuck cylinder 11 and protrudes from the outer circumferential surface of the collet 15 is located approximately at the center in the axial direction of the pressing area where the chuck cylinder 11 is pressed by the needle roller 13. It is located. On both sides of the key 18 in the axial direction, a space is formed between the chuck tube 11 and the collet 15 by the keyway 17.

In this embodiment, when the rotary tube 14 is rotated counterclockwise, the needle roller 13 in contact with the inner circumferential surface of the rotary tube 14 spirally revolves around the outer circumferential surface of the chuck tube 11 while rotating. It moves in the direction of arrow X in FIG. For this reason, the chuck tube 11
is elastically deformed in the radial direction, thereby tightening the shank portion 16a of the tool 16 from the outer circumferential side of the collet 15 in the chuck tube 11, and at the same time, strongly grips the shank portion 16a of the tool 16 via the collet 15. It turns out.

Then, as mentioned above, the tool 16 is moved to the collect 15.
When the holder main body 10 gripped through the holder body 10 is attached to the main shaft of a machine tool and the main shaft is rotated to cut the workpiece with the tool 16, the gripping force against the cutting resistance is exerted by the compression of the chuck tube 11. Rotation of the tool between the shank portion 16a and the chuck 11 is accomplished by a key 18 and a keyway 17.

Further, in this embodiment, since the rotation is prevented by the keyway 17 and the key 8, the tool 16 can be rotated by simply inserting the collet 15 into which the shank portion 16a of the tool 16 is fitted into the chuck cylinder 11. Collect 1 the anti-rotation function between the and chuck tube 11.
5, and as a result, there is no need to worry about forgetting to tighten the lock screw or loosening the lock screw, which is the case with conventional methods. It is a combination of a key groove 17 along the line and a key 18 that slidably engages with the key groove 17.
Since the shank portion 16a of the tool is inserted, it is easy to adjust the length of the tool in the axial direction, and the adjustment range can be extended.

Further, in this embodiment, the key 18 provided on the outer circumferential surface of the collet 15 into which the shank portion 16a of the tool 16 is fitted is operated by the needle roller 13 that presses the chuck tube 11 of the holder body 10 from the outer circumferential side. It is located approximately in the center of the area in the axial direction,
Since a keyway 17 is formed on the inner circumferential surface of the chuck tube 11 over almost the entire length of the pressing area in the axial direction, the concentricity of the holder body 10, the collet 15, and the tool 16, that is, the concentricity of the chuck tube 11 of the holder body 10. The gripping accuracy of the shank portion 16a via the collet 15 is increased.

That is, the gap between the key groove 17 provided on the inner circumferential surface of the chuck tube 11 and the key 18 protruding from the outer circumferential surface of the collet 15 is small, and the key 18 acts as a rigid body between the inner circumferential surface of the chuck tube 11 and the outer circumferential surface of the collet 15. When the chuck cylinder 11 is pressed from the outer circumferential side by the needle roller 13, the key groove 17 first deforms elastically in the circumferential direction. The elastic deformation of the inner diameter of the chuck cylinder 11 in the axial direction does not start uniformly in the direction of contraction of the inner diameter in the entire pressing area, but the contraction deformation starts from approximately the center of the pressing area in the axial direction, and this deformation As the deformation progresses, the deformation resistance increases, and this resistance and the deformation resistance in areas other than the pressed area gradually approach each other, and as a result, shrinkage deformation progresses from the center toward both ends in the axial direction, and the inner periphery of the chuck cylinder 11 The surface shrinks. Therefore, the contact between each surface of the keyway 17 provided on the inner circumferential surface of the chuck tube 11 and the key 18 creates resistance to the shrinkage deformation of the chuck tube 11, and the shrinkage deformation is free in the axially central portion. Therefore, as shown in FIG. 4c, the contraction and deformation temporarily stops, and during this time, the contraction and deformation of both sides of the key 18 proceed first. In other words, the chuck tube 11
The inner circumferential surface is deformed such that the central portion in the axial direction is deformed into a mountain shape, and then the central portion and both end portions are deformed to be averaged. Therefore, when the inner circumferential surface of the chuck tube 11 contracts evenly in the entire axial direction of the pressing area, even if there is a gap between the inner circumferential surface of the chuck 11 and the outer circumferential surface of the collect 15, the chuck tube 11 will contract. As the gap disappears, the axial runout between the chuck tube 11 and the collet 15 as shown in FIG.
When gripping is completed, the chuck tube 11, the collet 15 fitted therein, and the shank portion 16 of the tool 16
The concentricity with a is high and the gripping precision is good.

However, in the conventional one shown in FIG. 5, when the chuck tube 2 is inserted through the shank portion 6a of the cutter 6 and the collet 5, there is a gap between the chuck tube 2 and the collet 5, and as mentioned above, there is a gap between the chuck tube 2 and the collet 5. Chuck tube 2
The central part of the chuck cylinder 2 is deformed into a chevron-shaped axial cross-section, and the inner peripheral surface of the chuck cylinder 2 and the outer peripheral surface of the collet 5 come into contact at the central part in the axial direction, and then both ends come into contact with each other, so that the chuck cylinder 2 has only the gap. Correct 5 in a state of misalignment
When the chuck tube 2 is inserted and first comes into contact with the top of the chevron-shaped part on the inner surface of the chuck tube 2, the needle roller presses the entire pressing area in the axial direction in this state, so that when the grip is completed, the collet 5 of the chuck tube 2
Then, the shank portion 6a of the cutting tool 6 becomes axially runout, resulting in low concentricity. (See Figure 4b).

In addition, a key groove 1 provided on the inner circumferential surface of the chuck tube 11
7 and the key 18 provided on the outer circumferential surface of the collet 15 is large and the key 18 does not become a rigid body, the chuck cylinder 11 is contracted by the needle roller 13 from the loose state of the key groove 17 and the key 18. I will let you do it. In this case, in the process of eliminating the gap between the chuck tube 11 and the collect 15, the portion of the chuck tube 11 where the cross-sectional area is reduced in the key groove 17 is first pressed from the outer peripheral side by the needle roller 13. The chuck tube 11 begins to undergo contraction and deformation, and undergoes elastic deformation to bend at the keyway 17 portion, and as this deformation progresses, the contraction resistance of the keyway 17 portion increases.

Next, as the shrinkage resistance of the chuck cylinder 11 other than the keyway 17 increases and approaches the shrinkage resistance of the keyway 17, the other parts contract and deform behind the keyway 17. The chevron-shaped deformation at the center of the inner peripheral surface of the chuck tube 11 in the axial cross section of the chuck tube 11 occurs when the portion other than the key groove portion shrinks and deforms more than the key groove 17 portion, so in this embodiment, the key groove 17 is By providing this keyway, the amount of chevron-shaped deformation on the inner circumferential surface of the chuck tube 11 is smaller than that of the conventional one shown in FIG. The degree of concentricity between the cylinder 11, the collet 15, and the shank portion 16a of the tool 16 is increased.

Note that the above-mentioned effect of this embodiment is based on the collection 15.
This is achieved by bringing the outer circumferential surface of the shank portion 16a of the tool 16 into close contact with the inner circumferential surface of the tool 16 and keeping them concentric.

[Effects of the invention] As explained above, according to this invention, in a needle roller type chuck, the key protruding from the outer peripheral surface of the collet into which the shank of the tool is fitted is pressed by the needle roller against the inner peripheral surface of the chuck cylinder. Since the key is slidably engaged with a key groove formed over almost the entire axial length of the region and is disposed in the key groove at approximately the center of the pressing area in the axial direction, the following effects can be obtained.

That is, the engagement between the key and the keyway ensures that the tool is prevented from rotating through the collet, and there is no need to tighten a screw using a lock bolt or the like.
Furthermore, by arranging the key protruding from the outer circumferential surface of the collector at approximately the center in the axial direction of the pressing area of the key groove along the axial direction of the inner circumferential surface of the chuck cylinder,
The chuck tube, the collet, and the shank portion of the tool have good concentricity, and the holder body can grip the tool through the collet with high precision, so that the tool can be prevented from swinging around during machining.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing an embodiment of the chuck according to this invention, Fig. 2 is an end view taken from the - line in Fig. 1, Fig. 3 is a side sectional view of the collet, and Figs. 4 a and b. , c is an explanatory view comparing the chuck of this invention with a conventional chuck, and FIG. 5 is a side sectional view showing the conventional chuck. 10...Holder body, 11...Chuck tube, 1
2...Retainer, 13...Needle roller, 14
...Rotating tube, 15...Collection, 16...Tool,
16a...Shank portion, 17...Keyway, 18...
…Key.

Claims (1)

[Scope of utility model registration request] The outer circumferential surface of a chuck tube provided on the tip side of the holder body is formed into a tapered shape, and a rotating tube is fitted onto the outer circumferential surface of this chuck tube via a number of needle rollers.
The shank of the tool is inserted into the inner circumferential surface of the chuck tube through the collet, and as the rotary tube rotates, the chuck tube is elastically deformed and compressed by the needle roller. In the chuck for tightening and gripping the part, a key is protruded from the outer circumferential surface of the collet, and a key groove is formed on the inner circumferential surface of the chuck cylinder over almost the entire length in the axial direction of the pressing area by the needle roller. The above-mentioned key is slidably engaged with the key, and the key is disposed approximately in the axial center of the above-mentioned pressing area of the above-mentioned keyway. A chuck characterized by being formed on both sides of the key in the axial direction.